Improvement in recording instruments for the electric telegraph



W. THOMSON.-

. Electric Tel iegl gph Recorder.

N0. 109,688. Patented NOV. 29, 1870.

thatch fittin aunt Gtffitt.

WILLIAM THOMSON, or otaseow, SCOTLAND.

Letters Patent No. 109,688, dated November 29, 1870.

The Schedule mama to in than Letter! new; and making put of the m.

To all to whom-it may concern LIAM Tnonson do hereby declare il-IIOnature of .the

said invention, and in what manner the same is to be v performed, to beparticularly described and ascertained in and by the following statementthereof: That is to, '1 I This invention has-more especial] y for-itsobjectto produce an instrument capable of recording by permanent markssuch electric ,signals as have, up to the present time, been received bythe mirror-galvanome= ter invented by me. The peculiar merit of thatinstrument is that it cimtinnously indicates, with-approximateexaetitudc, the variations of strength in the reccived current. Themovement of the spotof light follows every variation in that current,and these varying strengths, being followed by the eye, can bc-in'terpreted under circumstances in which ordinaryiustruments, indicatingthe mere presence or absence of a given strength of current, would beuseless. if By my present improvements 1 am enable to con-- struct aninstrument which draws or marks on a strip of paper a curved orhroken'line, giving a graphic representation of the varying strength ofcurrent; or, if required, of electric potential at the receiving end ofthe cable, and gives a peruianentrecord ofevery feature of the effectdue to the 'senders action.

The instrument is available for the system of varying strength,including, of .course, the simplest system, viz: of two strengths, oftencalled positive and negative; or for the system of long and shortsignals, of which the Morse alphabet is the simplest type. fThedifiiculty in producing sue i-a recorder as this has been due to thediiiieulty of-obtaining marks from a very light body in rapid motionwithout impeding that motion. To effect this, I, according to myinvention, connect (either by direct attachment or by a stretchedthread-or fiber) to the body moved by the received current alightmarkiug-needle or tube, from the end of which'ink oxyother fluid isspurtetl upon paper.. (The signals which are to be recorded give rise tomotions of the marking end, which are parallel to the plane of thepaper. while thepaper is drawn along in its ownplane, and ma directionperpendicular to the line of the motions caused by the signals.) i Iemploy for the marking-needle, by preference, a capillary tube orabristle, dipping at one end into a stationary reservoir of iult'orother fluid, and I cause the ink or-other fluid to be spurted from ordrawn from. the opposite end bymeans of an electric force, or by meansof rapid vibrations maintained in. theneedle' or in the paper in adirection perpendicular to the plane of the paper. These vibrations maybe maintained. mechanically or pneumatically, as by the agency of sound,so that the paper receives ink by a succession of fine contacts, betweeneach of bristle is quite free to move. 8 When the electric method isused, the paper is drawn over a metal plate, electrified, say,positively, and the capillary tube is electrified, say, negatively,'anda powerful difference of potential is maintained between the tube andthemetal plate. such as would tend to cause a succession of sparks to passbetween them, and'wbieh in the circumstances produce a fine stream ofink, ora succession of fin'e'dots spurtcd'from the tube onto the paper,leaving a record of the position of the Wheat each inst-ant, and drawinga sensibly continuous line on the paper without impeding, by friction,the motion pf the tube as directed by the receiving instrument.

which the tube or' I prelbr to let the paper more in avertical plane,

and to use a small glass siphon, with its short legdipping in t-heink-resen'oir and its long log pointing ohliquely downward at the paper,and close to it.

A similar efiect is produced by the alternative methods described.

-, 1n connectionwitbthe above I use, as a receivingin'strument, apeculiar arrangement, in which the r'eceived current passes through a.very light coil of a small number of turns of fine wire. Part ofthiscoil is'placed in a very powerful magnetic field, produced bypermanent magnets or elcctro-magnets, which act with, great force on thecoilwheu the current passes through it. The coil is kept still, withoutany complete frame-Mark or bobbin, by the use of stifl' pieces (likebooms in the rigging of a ship) drawn asunder by threads or strongfibers stretched to fixed points, and

serving to support the coil while giving it the requisite freedom tomove and the requisite stability; and

In order that my said invention'may be most fully understood and readilycarried into effect, I will proceed to describe the drawing hereuntoannexed.

. Description of the Drawing.

Figure l is an elevation, aml

Figure 2, a plan, showing the principal parts of the recordinginstrument. I

A permanent compound steel magnet, N S, made, for convenience sake, of alarge number of straight steel bars, with a soft-iron j unction-pieceand soft-iron poles, is usedto produce a very intense magnetic field inthe deep narrow space separating the poles, shown in plan at 111, 11g.2. t

l igure it shows an elevation of a very light coil or skcin of linesilk-covered copper wire, stretched on a couple of light struts or boomsbetween I m and o p.

The side in n, composed solely of the line wire, is ibrmed'iuto a. thin,llat cake by being cement-ed with paralline.

The side I 0 is strengthened by a strong thread, to relieve the copperwire 'from strain, and the axisof' suspension is placed nearer thestrengthened side, as shown in the drawing. I I

The coil is suspended by two fine silk fibers, l1) and m g, in such a'position that the side at it hangs in the intense magnetic tield betweenthe poles of the large permanent magnet, and is free to oscillate in adirection parallel to the straight bars forming the mag nets.

The weight 10, hung from the bottom of the coil, keeps it in shape, andadds directing-truce to the coil, since any oscillation of the bilila-rsuspension will slightly liftthis weight. I

The peculiar construction of the coil reduces the momentum of the movingparts to a minimum. The form of the side Hi; 11, as a thin, flat strip,allows the poles of the permanent magnet to approach very closea 'ly, toform a very intense magnet-field, and the depth oi: the side in nexposes a considerable length of the wire in the coil to the action ofthe magnetism of the permanent magnets.

I have obtained good results with copper wire weighing about one-quartergrain per foot, and with coilscontaining about twenty turns.

The two ends of the wire forming the coilarc twisted round thesuspending fibers, one round each, as shown in fig. 3, and attached toterminals, B B, ti". 2, and

the received curreut-{com'eying the signals to'be recorded, is passedthrough the susp'uided coil from these. terminals.

So long as no current circulates through the cell it will hang directedsolely by the bifilar suspension, and

uhaifected by the presence of the powerful magnets; but as soon as acurrent is received through the side m h of the coil, it will beimpellcdout from between the poles, or further in bet-ween them, in adirection parallel to-the straight bars of the magnets. The direction ofthe impulse will depend on the direction of the curr'ent, and themagnitude of the deflectingforce will depend, cazteris par-thus, on thestrength of .-the received current.

The side at a of the coil will move backward or forward under the effectof the continually varying currents received through a submarine cable,and owing to the lightness of the coil, it will follow rapidly-varyingcurrents, so that at each moment its position will correspond to thestrength of the current at that instant. To do this, the directing forceof the bitilar suspension and weight should be adjnstedso that the freeoscillations of the coil when no current is passing are more rapid thanthe oscillations intended to be recordcd as signals."

The adjustment of the natural oscillations to the rate of signaling isfacilitated by the use of a damper, which will allow the adoption of asmaller directing power, and consequent greater range of deflection inthe marking point. I

Auyof the usual forms of: damper lnight be used, founded on the frictionof solids or fluids. Thus, a vane dipping in water may be employed; butgood results have been obtained by allowing a small spring to press onthe fiber 'r m to damp the vibrations.

.Thc receiving-coil follows the received current as readily as thelittle mirror and magnet in my reflect ing galvauometcr; but the samecurrentin my new instrument produces a much greater available force to'move the parts, and I can make use of this increase of force to allow arecording apparatusto be combined with the receiving-coil, in thefollowing manner:

A single silk fiber, at r, is attached at one end to the coilat the topof the side at w, and at; the other end to what I call the siphon'bf therecording instrument, shown in detail, and of full size, in Figure 4,and lettered t 'r s. t

The siphon is suspended with double threads, t a a: 'v, atone side,and-a single thread, 11 u, atthe other side, so as to be capable ofoscillating round'a horizonr tal axis.

The directing force of the double threads is 'adjusted so that thesiphon can follow the'movements of the side in -n, to which it isattached, keeping the single fiber T m always taut. v

he distance of the point of attachment 1' tiom the axis t 10 may beabout one-tenth the length of thelong leg of the siphon, so that anymotion ot'v the side at, a of the receiving-coil may be represented by aten-fold greater mot-ion at the end of the siphon. I use, as a siphon aline glass tube bent into the shape shown in fig. 4, which also showsthe paper on which the Big nals are to be recorded. This paper movespast the end in a direction perpendicular to that in which the end movesto indicate the signals. Theshort leg of the siphon dips into a dish ofink.

A brass plate, :2 y, across which the paper is drawn in front of the endof the siphon, is connected with an elcctricalanachinc, 'by which it iskept highly charged with electricity, whet-ms the siphonis in connectingwith the earth, and 'a-series of small and rapid discharges ofelectricity takes place between, the siphon and the plate, which causesthe inlcto be spirted from the siphon onto the paper." e The instrumentshould be so adjusted that the siphon will oscillate freely in adirection parallel to the plane of the paper from twice to ten times inthe time occupied inthe production of crew wave or signal or separatepart of a letter. 4

The ordinary electri l-maehine or'RuhmkorlPs coils might be used, but Iprefer to use my. new inductionapparatus, which can beconveniently-driven bythe clock-work used to supply the recording-paper,which may be of ordinary construction.- It is clearly shown at O, infigsrl and 2 i The following is a description of theinduction-apparatus:

Awhcel of vulcanitc, A A, fig.-5, with a number ofpieces of metal, a aa, &c., (called carriers for brevity,) attached toits' rim, is keptrotating rapidly round a fixed axis The carriers are very lightlytouched at opposite ends of a, diameter by two fixed tangent springs.One of these springs, B, is connected with the earth, and the other, C,with an insulated piece of metal, D, called the receiver, which isanalogous to the primeconductor of an ordinary elcctrimmachine.

The point of contact, I), of the'earthepringwith th carriers is exposedtoiihe'. influence ot'an electrified body, 1), called the conductor.When this is positively electrified, each carrier, when leaving thecontact with the earth-spring, carries away negative-electricity,

which it' gives up through the rcceiverrspriug to the receiver. Thereceiver and inductor mceachplaced so as to surround, as early as maybe, the point of contact of the corresponding spring. 1

g In fig. 5 the receiver andjnductpr'are out through at e and d to showthe carriers and contacts. l

From this description it will be seen that the inductor induces anegative charge on ali'the carriers inside it, and each carrier, insuccession, givcs'up this negative charge to the receiver, which.isconnected with the brass, plate a 3 fig. 4, fr m which it passes tothe siphon, as described. I The inductor E, ii". 5, for the good workingof the maehipe,-should be kept electrified to a high and constantpotential. This iscfl'ccted by an adj uuct called the replcuisher. Thercplenishcr is similar iii-shape connections are ditferently arranged.

Two of the Springs 0 0, called receiving-springs, are

connected to inductors E and D, and two springs B B, calledconnecting-springs, are joined together by a wire. The carrier touchesthe receiver-spring when wholly covered by the corresponding inductor.It touches the connccting-spriug shortly after breaking contact with'the receiver spring, and while still in great part covered by theinductor.

The action of the arrangement maybe described as follows:

Let one inductor, E,"'be in connection with the earth; let theconnecting-springs, with the wire joining them, be insulated, and theother inductor, D, electrified positively and connected with the otherinductor, E, of the inductiou-machine, fig. 5; let theaxis and carriersbe turned rapidly in the direction shown by the arrows, each carrier,after passing the contact 0, and while in contact with b, will receive anegative charge by induction, while contact-spring b, and the carrierwithwhich it is in contact, will at the same moment receive a positivecharge, these effects being produced by the redistribution of theelectricity in the insulated system composed of two clu' icrs, theconnectingsprings and wires under the influence of induction.

Immediately afterward contact is broken-at b and b, so that the twocarriers retain their positive and negative charges until connected withthe inductors by the springs c and c,- then the negative charge'will goto earth, through 1' and the positive charge will leave 4 the carrierinside I) to distribute itself on the outer surface of D, in accordancewith the well-known laws of induction. The repetition ofthis-action'leads to an indefinite accumulation of positive electricityon 'D, limited ,only by the perfection of its insulation, preventing thedispersion of the charge by conduction or by sparks. The charges ofpositive and negative electricityare indicated by the signs and on thecar- I'lelS- When discharged, 'or nearly discharged, an O is written onthe carriers. 1 k "1n the end view, fig; 6, the inductor L is removed toshow the wheel and carriers. 1 When the recordinginstrumcnt is at workthe brass plate and paper crossing it, being highly charged withstatical electricity,

attract the end of the siphon, and, under the influence of thisattractiou, and of a rapid vibration produced in the end of the siphon,and which is due to continual small electrical discharges, the ink fliesin a succession of line drops from the siphon to the paper. These dropsblend into a continuous line on the paper as it is drawn regularlytbrward. This line records the position of the end of the siphon at eachmoment as it is moved backward and forward across the paper by the silkfiber Mgat-tached to the side 1 a of. the receivingcoil. The line drawnon the paper is therefore acoutinuons curve corres 'ionding to themotions of the side.

at a of the receiving-coil, and therefore to the varying currentsproducing the motions and to the signals which these currents indimrte.When no current is received n simple straight line will 'be drawn alongthe paper; short, positive, and negative signals will draw small rippleson cithcrside of the zero-line.

Figure 7 shows the letters a b c as drawn by the instrument according tothe Steinhiel code.

Earth-currents will cause the siphon to make long sweeps from side toside on the paper, causing curves of small curvature, on which ,aresuperimposed the comparatively short curves of the signals. In line, theinstrument is adapted to record all signals which can he read on myreflecting galvanometer.

A spring or other adjustment may beused to bring the paper and thesiphon in'to'such a relative position that the marks may be near thecenter of the paper and the sensibility of the new recorder is such thatthecurrent from a single Daniells cell passing through a resistance ofeight thousand ohms gequal to the resistance of the whole Atlantic Cablewill produce a perfectly distinct signal, while the resistanceof thecoil in theinstrument itself need not exceed twenty ohms.

Toumltiply the power, when required, I use two or more light movablecoils, each attached to the markingneedlc by a connecting-fiber orfibers, whichv may be attached to the marking-needle'ncar its axis, soas to magnify the motion of the marking-end as compared.

with that of the receiving-coils. The magnification may be pushedfurther, if desired, by usinga multiplying train of two or more needles.

Mechanical vibrations may be maintained in the long leg of the siphon bysound instead of by electrical discharges. Thus the siphon may beattached by a single fiber to the end of a tuning-fork in vibration, thefiber being in a direction perpendicular to that in which the motionscorresponding to the signals take place, does not injurionsly impedethese motions, but, ori the contrary, may be used to gigs or adjust thedirecting-force. Instead of a tuning-fork, a spring set in vibration byan indented wheel, or a plate set vibrating by the air in a pipesounding a note, as in an organjerk the ink from the end of the siphonto the paper. The ink-drop at the end of the siphon may touch thevibrations might also be given from the paper itself, but I haveobtained the best results in the manner above described at length.

The recording mechanism might be attached to the common single needleinstrument, or the receiving-coil and magnet might be used as a relay orsingle-needle part of the coil is situate in a powerful magnetic field,

substantially as described.

Witnesses: WILLIAM THOMSON.

G. F. Wamms, Both ofNaTl flmcochurch Wnnnm M. HARIilB. street, London.

pipe, might be used togive the small vibrations which paper at the endof each vibration. The necessary instrument independently of therecording instrument.

tween strained threads or fibers in sucha position that

